In the wild, most birds seasonally reduce their rate of egg production, molt, and migrate. Vestiges of this natural cycle remain in domestic fowl: after 50 to 60 weeks of laying eggs, egg production becomes sporadic. Because the key to commercially successful egg production is to obtain consistent rates of egg laying from the hens, it is economically desirable to "force" the hens to molt when their rate of egg production becomes sporadic, and thereafter return them to a profitable level of egg production. Such procedures are generally discussed in Wilson, Fry, Harms and Arrington, Poultry Science 46, 1406-12 (1967), and Noles, Poultry Science 45, 50-57 (1965).
A combination of feed and water restriction and decreased daylength is commonly employed to induce a forced molt. Numerous experiments on these procedures have been conducted in efforts to improve their usefulness. Nevertheless, significant problems remain: foremost is that present commercial practices employ starvation procedures with an attendant high mortality rate, and these procedures are severely criticized for humanitarian reasons. In addition, such treatments often result in the post-molt production of low quality eggs which are overly large in size and have fragile, poor quality shells. Some egg producers attempt to reduce the high mortality rates which accompany a forced molt by subjecting their birds to less stressful procedures and only partially molting them. However, such incomplete forced molt procedures, sometimes referred to as "forced rest" procedures, result in a short period of post-treatment egg production; thus, economic returns are minimized.
Objects of the present invention are, accordingly, to provide a method of inducing laying hens to molt which does not involve starving or stressing the birds, allows the birds to be returned to efficient egg production, and causes the birds to thereafter produce good quality eggs of a good size, with good quality shells. Additional objects and advantages of our invention are discussed in detail below.